The present invention relates generally to powder conveying systems. More particularly, the present invention is directed to a powder feeding and metering apparatus for use in delivering powdered resin to a powdered resin spray nozzle. The invention finds particularly advantageous application in processes for applying powdered resin to fasteners.
A variety of vibratory powder feed systems have been known in the art for many years. Such feeding systems, dating back to the 1950s and 1960s, have included both rotationally vibrated bowls and linearly vibrated channels or troughs.
In the field of threaded fasteners, a need exists for feed systems useful for the application of powdered resins onto the fasteners. These resins, once applied, may serve any of several functions, including locking, sealing, lubrication or masking. Oftentimes the same feed apparatus will therefore be used with different resin powders, each having its own particle size distribution, specific gravity, coefficient of friction and perhaps other properties that affect its flow characteristics. Moreover, the same feed apparatus may be used with many different fastener sizes thereby requiring substantially different powder flow rates. Still further, the apparatus may be used with different spray assemblies, using one, two, three or even four spray nozzles.
As a result a need exists for a simple, efficient vibratory feed apparatus that offers great versatility while still accurately feeding and metering the powdered resin for spray application to threaded fasteners.